Braiding yarn made of expanded graphite

ABSTRACT

The present invention relates to a braiding yarn made of expanded graphite for a gland packing which is to be used in a shaft seal part of a fluid apparatus or the like. In the braiding yarn made of expanded graphite of the invention, a braiding yarn base material of the inner-reinforce type is used in which a plurality of reinforcing fibers are embedded in the longitudinal direction in an expanded graphite tape of a predetermined width, with forming gaps in the width direction. A twisting process is performed in a state where both the end portions in the width direction of the expanded graphite tape are bent so that both the end portions in the width direction of the expanded graphite tape are directed toward the inner side in the width direction of the base material. Alternatively, while twisting the base material both the end portions in the width direction of the expanded graphite tape are bent so that both end portions in the width direction are directed toward the inner side in the width direction. According to the invention, flaking of expanded graphite particles during a process of twisting the braiding yarn made of expanded graphite is reduced or prevented from occurring.

TECHNICAL FIELD

The present invention relates to a braiding yarn made of expandedgraphite for a gland packing which is to be used in a shaft seal part ofa fluid apparatus or the like, and more particularly to a braiding yarnmade of expanded graphite which can enhance the pressure resistance of agland packing.

BACKGROUND ART

Conventionally, as a braiding yarn for a gland packing which is to beused in a shaft seal part of a fluid apparatus or the like, known is,for example, a braiding yarn 3 shown in FIG. 13. In the braiding yarn 3,a plurality of reinforcing fibers 2, 2 are embedded in the longitudinaldirection with forming gaps in the width direction of an expandedgraphite tape 1 of a predetermined width.

In the case where a plurality of braiding yarns are braided to obtain agland packing, it may be requested to twist the braiding yarn 3 as shownin FIG. 14 in order to satisfactorily conduct the braiding.

However, the expanded graphite tape 1 is low in tensile strength andbrittle, and edges of both end portions 1 a, 1 b in the width directionhave low flaking resistance among expanded graphite particles. In edgesof both end portions 1 a, 1 b in the width direction, namely, expandedgraphite particles easily flake off In the case where the braiding yarn3 of the inner-reinforce type is twisted to obtain a twisted braidingyarn 10 made of expanded graphite, moreover, large tensile and shearingforces act on the edges of both end portions 1 a, 1 b in the widthdirection, and hence cracks are formed with starting from the edges ofboth the end portions 1 a, 1 b in the width direction. Therefore,expanded graphite particles in and in the vicinity of the edges of boththe end portions 1 a, 1 b in the width direction flake off.

When a plurality of braiding yarns 10 made of expanded graphite having atwisted structure are braided or twisted in a state where expandedgraphite particles flake off in this way, flaking of expanded graphiteparticles is further advanced during the braiding or twisting process.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a braiding yarn made ofexpanded graphite in which flaking of expanded graphite particles isreduced or prevented from occurring.

In order to attain the object, the braiding yarn made of expandedgraphite according to the invention is characterized in that, in abraiding yarn made of expanded graphite which is to be used in a glandpacking, the braiding yarn is twisted so that at least one end portionin a width direction of a braiding yarn base material in whichreinforcing fibers are embedded in an expanded graphite tape is directedtoward an inner side in the width direction of the braiding yarn basematerial. According to the invention, since a twisting process isperformed so that at least one end portion in the width direction of abraiding yarn base material is directed toward the inner side in thewidth direction of the braiding yarn base material, large tensile andshearing forces do not directly act on the edges of the one end portionduring a twisting process, and hence occurrence of cracks from the edgesof the one end portion and flaking of expanded graphite particles due tothe occurrence of cracks can be reduced.

The other braiding yarn made of expanded graphite according to theinvention is characterized in that, in a braiding yarn made of expandedgraphite which is to be used in a gland packing, the braiding yarn istwisted so that at least one end portion in a width direction of abraiding yarn base material in which reinforcing fibers are embedded inan expanded graphite tape is directed toward an inner side in the widthdirection of the braiding yarn base material and a portion between bothend portions in the width direction is bent. According to the invention,in addition to the function that, during a twisting process, largetensile and shearing forces do not directly act on the edges of the oneend portion and occurrence of cracks from the edges of the one endportion and flaking of expanded graphite particles due to the occurrenceof cracks can be reduced, since the portion between both the endportions in the width direction of the braiding yarn base material isbent, the dimension in the width direction of the braiding yarn basematerial can be reduced, the twisting process is facilitated, andtwisting workability can be improved.

The further braiding yarn made of expanded graphite according to theinvention is characterized in that, in a braiding yarn made of expandedgraphite which is to be used in a gland packing, a braiding yarn basematerial in which reinforcing fibers are embedded in an expandedgraphite tape and part of expanded graphite particles on a side of asurface of the expanded graphite tape are removed by a blasting processand is twisted. According to the invention, part of expanded graphiteparticles which are on the side of the surface of the expanded graphitetape, and which are highly oriented at a high density where crackseasily occur are removed by the blasting process. During the twistingprocess, even when a large tensile force acts on the end portions in thewidth direction of the braiding yarn base material, therefore,occurrence of cracks from the end portions and flaking of expandedgraphite particles due to the occurrence of cracks can be reduced.

The still further braiding yarn made of expanded graphite according tothe invention is characterized in that, in a braiding yarn made ofexpanded graphite which is to be used in a gland packing, the braidingyarn is twisted so that at least one end portion in a width direction ofa braiding yarn base material in which reinforcing fibers are embeddedin an expanded graphite tape and part of expanded graphite particles ona side of a surface of the expanded graphite tape are removed by ablasting process and is directed toward an inner side in the widthdirection of the braiding yarn base material. According to theinvention, in addition to the function that, during the twistingprocess, large tensile and shearing forces do not directly act on theedges of the one end portion and occurrence of cracks from the edges ofthe one end portion and flaking of expanded graphite particles due tothe occurrence of cracks can be reduced, since part of the expandedgraphite particles which are on the side of the surface of the expandedgraphite tape, and which are highly oriented at a high density wherecracks easily occur are removed by the blasting process, a functionthat, during the twisting process, even when a large tensile force actson both end portions in the width direction of the braiding yarn basematerial, therefore, occurrence of cracks from the end portions andflaking of expanded graphite particles due to the occurrence of crackscan be reduced is added. Consequently, occurrence of cracks and flakingof expanded graphite particles due to the occurrence of cracks can bereduced more surely.

The still further braiding yarn made of expanded graphite according tothe invention is characterized in that, in a braiding yarn made ofexpanded graphite which is to be used in a gland packing, the braidingyarn is twisted so that at least one end portion in a width direction ofa braiding yarn base material in which reinforcing fibers are embeddedin an expanded graphite tape and part of expanded graphite particles ona side of a surface of the expanded graphite tape are removed by ablasting process is directed toward an inner side in the width directionof the braiding yarn base material and a portion between both endportions in the width direction is bent. According to the invention, inaddition to the function that, during the twisting process, largetensile and shearing forces do not directly act on the edges of the oneend portion and occurrence of cracks from the edges of the one endportion and flaking of expanded graphite particles due to the occurrenceof cracks can be reduced, since the portion between both end portions inthe width direction is bent, the dimension in the width direction of thebraiding yarn base material can be reduced, the twisting process isfacilitated, and twisting workability can be improved.

The still further braiding yarn made of expanded graphite according tothe invention is characterized in that, in a braiding yarn made ofexpanded graphite which is to be used in a gland packing, a braidingyarn base material in which reinforcing fibers are embedded in anexpanded graphite tape and part of expanded graphite particles on a sideof a surface of the expanded graphite tape are removed by a blastingprocess is twisted. According to the invention, since part of theexpanded graphite particles which are on the side of the surface of theexpanded graphite tape, and which are highly oriented at a high densitywhere cracks easily occur are removed by the blasting process. Duringthe twisting process, even when a large tensile force acts on the endportions in the width direction of the braiding yarn base material,therefore, occurrence of cracks from the end portions and flaking ofexpanded graphite particles due to the occurrence of cracks can bereduced. Consequently, occurrence of cracks and flaking of expandedgraphite particles due to the occurrence of cracks can be prevented moresurely.

The still further braiding yarn made of expanded graphite according tothe invention is characterized in that, in the braiding yarn basematerial, the surface side of the expanded graphite tape on which theremoval by the blasting process is performed is impregnated with alubricating material. According to the invention, part of expandedgraphite particles which are on the side of the surface of the expandedgraphite tape, and which are highly oriented at a high density areremoved by the blasting process, whereby gaps of high permeability areformed among the expanded graphite particles. Therefore, a lubricatingmaterial easily permeates through the gaps. When the gaps areimpregnated with a lubricating material, it is possible to improve thelubricity, the adaptability, and the like of the braiding yarn made ofexpanded graphite.

The still further braiding yarn made of expanded graphite according tothe invention is characterized in that the reinforcing fibers areembedded in the expanded graphite tape via an adhesive agent. Accordingto the invention, high tensile strength of the reinforcing fibers issurely given to the braiding yarn made of expanded graphite by theadhesive strength of the adhesive agent, so that the tensile strength ofthe braiding yarn made of expanded graphite can be enhanced.

In each of the above-mentioned variants of the invention, “so that atleast one end portion in a width direction of a braiding yarn basematerial is directed toward an inner side in the width direction of thebraiding yarn base material” means that, during the twisting process,one end portion only is directed toward the inner side in the widthdirection of the braiding yarn base material. For example, therefore,the one end portion may be previously bent toward the inner side in thewidth direction of the braiding yarn base material before the twistingprocess, and, during the twisting process, the one end portion may becaused to be directed toward the inner side in the width direction ofthe braiding yarn base material. Alternatively, the one end portion maybe previously formed into a curled shape, a spiral shape, an obliquelyinward-directed shape, or another shape, and, during the twistingprocess, the one end portion may be caused to be directed toward theinner side in the width direction of the braiding yarn base material.

The number of the braiding yarn base material is not restricted to one.A plurality of braiding yarn base materials may be stacked together, andthe braiding yarn base materials may be twisted so that at least one endportion in a width direction of each of the braiding yarn base materialsis directed toward an inner side in the width direction of the braidingyarn base material.

It is a matter of course that both end portions in a width direction ofa braiding yarn base material may be directed toward an inner side inthe width direction of the braiding yarn base material.

Furthermore, the terms that a portion between both end portions in thewidth direction of the braiding yarn base material is bent mean that,during the twisting process, a portion between both end portions in thewidth direction is requested only to be bent.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a perspective view of a braiding yarn base material in anembodiment of the invention.

FIG. 1B is a perspective view of a braiding yarn base material in anembodiment of the invention.

FIG. 1C is a perspective view showing an embodiment of the invention.

FIG. 2 is a perspective view showing another embodiment of theinvention.

FIG. 3 is a perspective view showing a further embodiment of theinvention.

FIG. 4 is a perspective view showing a still further embodiment of theinvention.

FIG. 5A is a perspective view of a braiding yarn base material in astill further embodiment of the invention.

FIG. 5B is a perspective view showing the still further embodiment ofthe invention.

FIG. 6A is a perspective view of a braiding yarn base material in astill further embodiment of the invention.

FIG. 6B is a perspective view of a braiding yarn base material in thestill further embodiment of the invention.

FIG. 6C is a perspective view showing the still further embodiment ofthe invention.

FIG. 7 is a perspective view showing a still further embodiment of theinvention.

FIG. 8 is a perspective view showing a still further embodiment of theinvention.

FIG. 9 is a perspective view showing a still further embodiment of theinvention.

FIG. 10 is a partial enlarged section view showing a still furtherembodiment of the invention.

FIG. 11 is a partial enlarged section view showing a still furtherembodiment of the invention.

FIG. 12 is a section view showing a modification of a braiding yarn basematerial.

FIG. 13 is a perspective view showing an example of a braiding yarn basematerial of the inner-reinforce type.

FIG. 14 is a perspective view showing an example of a conventionalbraiding yarn made of expanded graphite.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the invention will be describedwith reference to the drawings. FIGS. 1A to 1C are perspective viewsshowing embodiments of the braiding yarn made of expanded graphite ofthe invention. Referring to these figures, in the braiding yarn 10 madeof expanded graphite, a braiding yarn base material 3 of theinner-reinforce type is used in which, as shown in FIG. 1A, a pluralityof reinforcing fibers 2, 2 are embedded in the longitudinal direction inan expanded graphite tape 1 of a predetermined width, with forming gapsin the width direction. Both the end portions in the width direction ofthe braiding yarn base material 3, i.e., both the end portions 1 a, 1 bin the width direction of the expanded graphite tape 1 are bent so as tobe directed toward the inner side in the width direction of the braidingyarn base material 3 as shown in FIG. 1B. Thereafter, as shown in FIG.1C, the braiding yarn base material is twisted by bending a centerportion in the width direction of the braiding yarn base material 3,into a V-like shape in the longitudinal direction, or the braiding yarnbase material 3 of the 0-reinforce type of FIG. 1B is twisted.

As the reinforcing fibers 2, used is one selected from organic fiberssuch as cotton, rayon, phenol, aramid, PBO, PBI, PTFE, PPS, and PEEK;one selected from inorganic fibers such as glass fiber, carbon fiber,and ceramic fiber; or one selected from metal wires such as stainlesssteel, inconel, and monel. Of course, the organic fibers, the inorganicfibers, and the metal wires may be adequately selected to be combinedlyused.

FIG. 2 is a perspective view showing another embodiment of the braidingyarn made of expanded graphite of the invention. In the figure, in thebraiding yarn 10 made of expanded graphite, a braiding yarn basematerial 3 of the inner-reinforce type is used in which a plurality ofreinforcing fibers 2, 2 are embedded in the longitudinal direction in anexpanded graphite tape 1 of a predetermined width, with forming gaps inthe width direction. Only one end portion 1 a in the width direction ofthe braiding yarn base material 3 is bent so as to be directed towardthe inner side in the width direction of the braiding yarn base material3. Thereafter, the braiding yarn base material is twisted by bending acenter portion in the width direction of the braiding yarn base material3, into a V-like shape in the longitudinal direction, or the braidingyarn base material 3 is twisted without performing bending into a V-likeshape.

FIG. 3 is a perspective view showing a further embodiment of thebraiding yarn made of expanded graphite of the invention. In the figure,in the braiding yarn 10 made of expanded graphite, a braiding yarn basematerial 3 of the inner-reinforce type is used in which a plurality ofreinforcing fibers 2, 2 are embedded in the longitudinal direction in anexpanded graphite tape 1 of a predetermined width, with forming gaps inthe width direction. Both the end portions 1 a, 1 b in the widthdirection of the expanded graphite tape 1 are curled so that both theend portions in the width direction of the braiding yarn base material3, i.e., both the end portions 1 a, 1 b in the width direction of theexpanded graphite tape 1 are directed toward the inner side in the widthdirection of the braiding yarn base material 3, and a plurality ofplaces between the end portions 1 a, 1 b are bent in the longitudinaldirection. Thereafter, the braiding yarn base material is twisted.Alternatively, the end portions 1 a, 1 b are curled while twisting thebraiding yarn base material 3 of the inner-reinforce type, and aplurality of places between the end portions 1 a, 1 b are bent in thelongitudinal direction. The end portions 1 a, 1 b in the width directionof the expanded graphite tape 1 are directed toward the inner side inthe width direction of the braiding yarn base material 3.

FIG. 4 is a perspective view showing a still further embodiment of thebraiding yarn made of expanded graphite of the invention. In the figure,in the braiding yarn 10 made of expanded graphite, a braiding yarn basematerial 3 of the inner-reinforce type is used in which a plurality ofreinforcing fibers 2, 2 are embedded in the longitudinal direction in anexpanded graphite tape 1 of a predetermined width, with forming gaps inthe width direction. Both the end portions la in the width direction ofthe expanded graphite tape 1 are curled so that only one end portion inthe width direction of the braiding yarn base material 3, i.e., one endportion la in the width direction of the expanded graphite tape 1 isdirected toward the inner side in the width direction of the braidingyarn base material 3, and a plurality of places between the end portions1 a, 1 b are bent in the longitudinal direction. Thereafter, thebraiding yarn base material is twisted. Alternatively, the end portions1 a are curled while twisting the braiding yarn base material 3 of theinnerreinforce type, and a plurality of places between the end portions1 a, 1 b are bent in the longitudinal direction. The end portions 1 a, 1b in the width direction of the expanded graphite tape 1 are directedtoward the inner side in the width direction of the braiding yarn basematerial 3.

FIGS. 5A and 5B are perspective views showing a still further embodimentof the braiding yarn made of expanded graphite of the invention. Inthese figures, in the braiding yarn 10 made of expanded graphite, abraiding yarn base material 3 of the inner-reinforce type is used inwhich, as shown in FIG. 5A, a plurality of reinforcing fibers 2, 2 areembedded in the longitudinal direction in an expanded graphite tape 1 ofa predetermined width, with forming gaps in the width direction. Part ofthe expanded graphite particles 5 which are on the side of the surfaceof the braiding yarn base material 3, and which are highly oriented at ahigh density are removed by a blasting process. Thereafter, the braidingyarn base material is twisted with bending a center portion in the widthdirection of the braiding yarn base material 3, into a V-like shape inthe longitudinal direction as shown in FIG. 5B, or the braiding yarnbase material is twisted without performing bending into a V-like shape.

The expanded graphite particles which are on the side of the surface ofthe expanded graphite tape 1, and which are highly oriented at a highdensity are removed away by a n microblasting process using particleswhich are smaller in diameter than the expanded graphite particles.Specifically, a blasting process is performed using fine particles (forexample, a particle diameter of 15 μm) of SiC or the like at an airpressure of 2 kg/cm² from a position which is separated by 150 mm fromthe outer face of the expanded graphite tape 1. When a microblastingprocess is performed in this way, the flaking resistance of the expandedgraphite particles which has been in a range of 30 to 40 g before theblasting process is increased to a range of 140 to 150 g.

FIGS. 6A to 6C are perspective views showing a still further embodimentof the braiding yarn made of expanded graphite of the invention. Inthese figures, in the braiding yarn 10 made of expanded graphite, abraiding yarn base material 3 of the inner-reinforce type is used inwhich, as shown in FIG. 6A, a plurality of reinforcing fibers 2, 2 areembedded in the longitudinal direction in an expanded graphite tape 1 ofa predetermined width, with forming gaps in the width direction. Part ofexpanded graphite particles 5 which are on the side of the surface ofthe braiding yarn base material 3, and which are highly oriented at ahigh density are removed by a blasting process. Both the end portions inthe width direction of the braiding yarn base material 3, i.e., both theend portions 1 a, 1 b in the width direction of the expanded graphitetape 1 are bent so as to be directed toward the inner side in the widthdirection of the braiding yarn base material 3 as shown in FIG. 6B.Thereafter the braiding yarn base material is twisted with bending acenter portion in the width direction of the braiding yarn base material3, into a V-like shape in the longitudinal direction as shown in FIG.6C, or the braiding yarn base material 3 of the innerreinforce type ofFIG. 6B is twisted without performing bending into a V-like shape.

FIG. 7 is a perspective view showing a still further embodiment of thebraiding yarn made of expanded graphite of the invention. In the figurein the braiding yarn 10 made of expanded graphite, a braiding yarn basematerial 3 of the inner-reinforce type is used in which a plurality ofreinforcing fibers 2, 2 are embedded in the longitudinal direction in anexpanded graphite tape 1 of a predetermined width, with forming gaps inthe width direction. Part of expanded graphite particles 5 which are onthe side of the surface of the braiding yarn base material 3, and whichare highly oriented at a high density are removed by a microblastingprocess. Only one end portion in the width direction of the braidingyarn base material 3, i.e., one end portion la in the width direction ofthe expanded graphite tape 1 is bent so as to be directed toward theinner side in the width direction of the braiding yarn base material 3.Thereafter, the braiding yarn base material is twisted with bending acenter portion in the width direction of the braiding yarn base material3, into a V-like shape in the longitudinal direction, or the braidingyarn base material 3 is twisted without performing bending into a V-likeshape.

FIG. 8 is a perspective view showing a still further embodiment of thebraiding yarn made of expanded graphite of the invention. In the figure,in the braiding yarn 10 made of expanded graphite, a braiding yarn basematerial 3 of the inner-reinforce type is used in which a plurality ofreinforcing fibers 2, 2 are embedded in the longitudinal direction in anexpanded graphite tape 1 of a predetermined width, with forming gaps inthe width direction. Part of expanded graphite particles 5 which are onthe side of the surface of the braiding yarn base material 3, and whichare highly oriented at a high density are removed by a microblastingprocess. Both the end portions 1 a, 1 b in the width direction of theexpanded graphite tape 1 are curled so that both the end portions in thewidth direction of the braiding yarn base material 3, i.e., both the endportions 1 a, 1 b in the width direction of the expanded graphite tape 1are directed toward the inner side in the width direction of thebraiding yarn base material 3, and a plurality of places between the endportions 1 a, 1 b are bent in the longitudinal direction. Thereafter,the braiding yarn base material is twisted. Alternatively, the endportions are curled while twisting the braiding yarn base material 3 ofthe inner-reinforce type which has undergone a microblasting process,and a plurality of places between the end portions 1 a, 1 b are bent inthe longitudinal direction. The end portions 1 a, 1 b in the widthdirection of the expanded graphite tape 1 are directed toward the innerside in the width direction of the braiding yarn base material 3.

FIG. 9 is a perspective view showing a still further embodiment of thebraiding yarn made of expanded graphite of the invention. In the figure,in the braiding yarn 10 made of expanded graphite, a braiding yarn basematerial 3 of the inner-reinforce type is used in which a plurality ofreinforcing fibers 2, 2 are embedded in the longitudinal direction in anexpanded graphite tape 1 of a predetermined width, with forming gaps inthe width direction. Part of expanded graphite particles 5 which are onthe side of the surface of the braiding yarn base material 3, and whichare highly oriented at a high density are removed by a microblastingprocess. One end portion 1 a in the width direction of the expandedgraphite tape 1 is curled so that only one end portion in the widthdirection of the braiding yarn base material 3, i.e., the end portion 1a in the width direction of the expanded graphite tape 1 is directedtoward the inner side in the width direction of the braiding yarn basematerial 3, and a plurality of places between the end portions 1 a, 1 bare bent in the longitudinal direction. Thereafter, the braiding yarnbase material is twisted. Alternatively, the one end portion 1 a iscurled while twisting the braiding yarn base material 3 of theinner-reinforce type, and a plurality of places between the end portions1 a, 1 b are bent in the longitudinal direction. The end portion 1 a inthe width direction of the expanded graphite tape 1 is directed towardthe inner side in the width direction of the braiding yarn base material3.

In each of the above-mentioned braiding yarn base materials 3, as shownin FIG. 10, when part of expanded graphite particles which are on theside of the surface of the expanded graphite tape 1, and which arehighly oriented at a high density are removed away by a microblastingprocess using particles which are smaller in diameter than the expandedgraphite particles, gaps c are formed among the expanded graphiteparticles. Therefore, a lubricating material easily permeates throughthe gaps c among the expanded graphite particles. When the gaps c areimpregnated with: various kinds of rubber such as nitrile rubber (NBR),and chloroprene rubber (CR); a fluororesin such as PTFE described above;various kinds of synthetic resins such as epoxy, phenol, nylon, andpolyetylene; or various kinds of oil such as silicone, it is possible toimprove the adaptability, the lubricity, and the like of the braidingyarn base material 3.

In each of the above-mentioned braiding yarn base materials 3, as shownin FIG. 11, when the whole periphery of each of the plurality ofreinforcing fibers 2 which are embedded in the longitudinal direction inthe expanded graphite tape 1 of the predetermined width, with forminggaps in the width direction may be bonded to the expanded graphite tape1 via an adhesive agent 6. Alternatively, part of the outer periphery ofeach of the plurality of reinforcing fibers 2 may be bonded to theexpanded graphite tape 1 via the adhesive agent 6. According to thisconfiguration, breakage of the yearn can be prevented from occurringduring the twisting process, by the braiding yarn base material 3 inwhich the high tensile strength of the reinforcing fibers 2 is surelygiven to the expanded graphite tape 1 of low tensile strength.

In each of the above-mentioned braiding yarn base materials 3, as shownin FIG. 12, for example, a reinforcing wire 2A such as a metal wire maybe placed in a center portion in the width direction of the surface ofthe braiding yarn base material 3, or the reinforcing wire 2A may beplaced in each of the bent valleys between the end portions shown inFIG. 3, FIG. 4, FIG. 8, and FIG. 9. According to this configuration, thetensile strength of the braiding yarn base material 3 can be furtherimproved, so that breakage of the yearn can be prevented from occurringduring the twisting process.

INDUSTRIAL APPLICABILITY

As described above, according to the braiding yarn made of expandedgraphite of the invention, even when the braiding yarn base material istwisted, flaking of expanded graphite particles is reduced or preventedfrom occurring.

According to the invention, when the surface side of the expandedgraphite tape is previously removed by a blasting process, impregnationwith a lubricating agent is facilitated, and the adaptability, thelubricity, and the like of the braiding yarn base material can beimproved.

According to the invention, when the surface side of the expandedgraphite tape is previously removed away by a blasting process,impregnation with a lubricating agent is facilitated, and theadaptability, the lubricity, and the like of the braiding yarn basematerial can be improved.

According to the invention, when reinforcing fibers are embedded in theexpanded graphite tape via an adhesive agent, high tensile strength ofthe reinforcing fibers is surely given to the expanded graphite tape oflow tensile strength, so that breakage of the yearn can be preventedfrom occurring during a twisting process.

What is claimed is:
 1. A braiding yarn made of expanded graphite whichis to be used in a gland packing, wherein said braiding yarn is formedso that at least one end portion in a width direction of a braiding yarnbase material in which reinforcing fibers are embedded in an expandedgraphite tape is bent toward an inner side in the width direction ofsaid braiding yarn base material.
 2. A braiding yarn made of expandedgraphite which is to be used in a gland packing, wherein said braidingyarn is formed so that at least one end portion in a width direction ofa braiding yarn base material in which reinforcing fibers are embeddedin an expanded graphite tape is bent toward an inner side in the widthdirection of said braiding yarn base material and a portion between bothend portions in the width direction is bent, and said braiding yarn basematerial is consequently twisted.
 3. A braiding yarn made of expandedgraphite according to claim 2, wherein said reinforcing fibers areembedded in said expanded graphite tape via an adhesive agent.
 4. Abraiding yarn made of expanded graphite which is to be used in a glandpacking, wherein said braiding yarn is formed so that at least one endportion in a width direction of a braiding yarn base material in whichreinforcing fibers are embedded in an expanded graphite tape and part ofexpanded graphite particles on a side of a surface of said expandedgraphite tape are removed away by a blasting process is bent toward aninner side in the width direction of said braiding yarn base material,and said braiding yarn base material is consequently twisted.
 5. Abraiding yarn made of expanded graphite which is to be used in a glandpacking, wherein said braiding yarn is formed so that at least one endportion in a width direction of a braiding yarn base material in whichreinforcing fibers are embedded in an expanded graphite tape and part ofexpanded graphite particles on a side of a surface of said expandedgraphite tape are removed away by a blasting process is bent toward aninner side in the width direction of said braiding yarn base materialand a portion between both end portions in the width direction is bent,and said braiding yarn base material is consequently twisted.
 6. Abraiding yarn made of expanded graphite according to claim 5, whereinthe surface side of said expanded graphite tape on which the removal bythe blasting process on said braiding yarn base material is performed isimpregnated with a lubricating material.
 7. A braiding yarn made ofexpanded graphite according to claim 5, wherein said reinforcing fibersare embedded in said expanded graphite tape via an adhesive agent.
 8. Abraiding yarn made of expanded graphite which is to be used in a glandpacking, wherein a braiding yarn base material in which reinforcingfibers are embedded in an expanded graphite tape and part of expandedgraphite particles on a side of a surface of said expanded graphite taperemoved by a blasting process is twisted, and wherein the surface sideof said expanded graphite tape on which the removal by the blastingprocess on said braiding yarn base material is performed is impregnatedwith a lubricating material.
 9. A braiding yarn made of expandedgraphite which is to be used in a gland packing, wherein said braidingyarn is twisted so that at least one end portion in a width direction ofa braiding yarn base material in which reinforcing fibers are embeddedin an expanded graphite tape and part of expanded graphite particles ona side of a surface of said expanded graphite tape removed by a blastingprocess is directed toward an inner side in the width direction of saidbraiding yarn base material, and wherein the surface side of saidexpanded graphite tape on which the removal by the blasting process onsaid braiding yarn base material is performed is impregnated with alubricating material.
 10. A braiding yarn made of expanded graphitewhich is to be used in a gland packing, wherein said braiding yarn istwisted so that at least one end portion in a width direction of abraiding yarn base material in which reinforcing fibers are embedded inan expanded graphite tape is directed toward an inner side in the widthdirection of said braiding yarn base material, and wherein saidreinforcing fibers are embedded in said expanded graphite tape via anadhesive agent.
 11. A braiding yarn made of expanded graphite which isto be used in a gland packing, wherein a braiding yarn base material inwhich reinforcing fibers are embedded in an expanded graphite tape andpart of expanded graphite particles on a side of a surface of saidexpanded graphite tape removed by a blasting process is twisted, andwherein said reinforcing fibers are embedded in said expanded graphitetape via an adhesive agent.
 12. A braiding yarn made of expandedgraphite which is to be used in a gland packing, wherein said braidingyarn is twisted so that at least one end portion in a width direction ofa braiding yarn base material in which reinforcing fibers are embeddedin an expanded graphite tape and part of expanded graphite particles ona side of a surface of said expanded graphite tape are removed away by ablasting process is directed toward an inner side in the width directionof said braiding yarn base material, and wherein said reinforcing fibersare embedded in said expanded graphite tape via an adhesive agent.
 13. Abraiding yarn made of expanded graphite which is to be used in a glandpacking, wherein a braiding yarn base material in which reinforcingfibers are embedded in an expanded graphite tape and part of expandedgraphite particles on a side of a surface of said expanded graphite taperemoved by a blasting process is twisted, wherein the surface side ofsaid expanded graphite tape on which the removal by the blasting processon said braiding yarn base material is performed is impregnated with alubricating material, and wherein said reinforcing fibers are embeddedin said expanded graphite tape via an adhesive agent.